Butterfly Valves

Slurry Tuff along Bray have a wide range of Butterfly values suited to a diverse range of environments.

RESILIENT SEATED BUTTERFLY VALVES

butterfly valves

DESIGN FEATURES

1 MOLDED-IN SEAT:

Tightly controlled molding processproduces accurate and repeatable dimensions,

whichleads to consistently lower torques over the valve’slifetime.

2 PRECISION PROFILED DISC SEALING EDGE:

Extends the valve life by reducing seat wear.

3 ROBUST FLANGE SEALING:

Tear-dropped shaped seat face enables tight sealing with a wide variety of
industrial flanges.

4 ISO 5211 TOP FLANGE:

Direct mounting capabilitybetween the valve and Bray

actuation reduces package height and complexity.

5 UPPER AND LOWER STEM BEARINGS:

Reduce operating torque and increase reliability

in high cycle applications.

6 END OF LINE CAPABILITY:

Lug style valve allows for sealing at full rated pressure even when the
downstream flange is removed.

 

LOW PRESSURE DISC

Bray offers a low pressure disc for NPS 2-24 (DN 50-600)
Series 3W/3L valves. The purpose of reducing the disc
diameter is to decrease the seating/unseating torque and
extend the seat life in low pressure applications.

By reducing the disc diameter, the interference between
the disc outside diameter and seat inside diameter is
decreased and the valve pressure rating, which is a function
of this interference, is reduced to 50 psi (3.4 bar). Less
interference between the disc and seat results in reduced
seating/unseating torque. Lower seating/unseating torque
may allow for the use of a smaller actuator on the valve. In
other applications where abrasive dry bulk materials such
as cement, sugar, plastic, pellets, flour, etc., are generally
pneumatically conveyed at 50 psi (3.4 bar) or less, the
reduced disc diameter not only reduces the seating/
unseating torque but, increases the service life of the seat
as well.

Bray does the following to differentiate low pressure discs
from full diameter discs:
> Metal discs: An “R” is stamped above the part number to
indicate a reduced diameter, low pressure disc.
> Nylon 11 coated discs: Discs are differentiated by the
color of the Nylon 11:
> Gray: Standard pressure
> White: Low pressure

 

resilient sealed butterfly valves

FLANGE BOLTING TENSIONING

 

Bray Butterfly Valves with Metal Mating Flanges

A frequently asked question at Bray is “What torque do
I apply to the flange bolts to insure the valve is properly
installed?”. Initially this seems to be a simple request until
all of the factors are analyzed. The installation of a valve
requires several components: the valve, mating flanges, nuts,
bolts and studs. Each is supplied by different manufacturers
and each has different characteristics. The proper torque for
one combination may be too much or too little for a second
combination. The following is a list of information which
needs to be known in order to start calculating the torque
requirements.

Valve

Type
> Size
> Materials of construction (body)
> Surface finishes / surface conditions

Flange

Type
> Size
> Finish / both sides
> Condition of flange / surface contamination

Bolt (or Stud)

Type
> Materials of construction
> Surface conditions

Nut

Type
> Materials of construction
> Surface conditions

Lubrication

Type
> Coverage

General Factors

Temperature and relative humidity at the time of
installation

> Speed at which bolts are turned

Note: The elastomer valve seat manufactured by Bray also
acts as the flange gasket. No additional gaskets are required
or recommended. Other valve styles which do not have
integral gaskets will need to have this component supplied.
The characteristics of this component will also need to be
considered.

Complete knowledge of all relevant conditions is almost
impossible to obtain. As a result, the computation of the
exact torque requirement is not practical. No reputable
manufacturer can provide accurate information when so
many outside factors are present.

The International Fasteners Institute covers some of the
details required to “compute” a torque value. Even with this
information the use of a torque wrench is only considered to
be 25% accurate. Based on the difficulty and inaccuracy of
using this method, Bray recommends the use of the “Turn of
the Nut” method.

“Turn of the Nut” Tightening
(For Standard Iron and Steel Flanges)

**For Non-Metallic or non-standard flanges, follow the
manufacturers installation procedures.

1. The valve and flange faces must be aligned parallel to each
other. For rubber seated butterfly valves manufactured by
Bray, it is required that the valve be fully opened prior to
the tightening of the flange bolts.

2. After aligning the holes in a joint, sufficient bolts shall be
placed and brought to a “snug-tight” condition to ensure
that the parts of the joint are brought into full contact with
each other. “Snug-tight” is the tightness attained by the
full effort of a man using a wrench.

3. Following the initial snugging operation, bolts shall be
placed in any remaining holes and brought to snugtightness. Re-snugging may be necessary in large joints.

4. Tighten opposite bolts in sequence to insure even pressure
around the entire flange.

5. When all bolts are snug-tight, each bolt in the joint then
shall be tightened additionally by the applicable amount of
nut rotation given in Note 1. During tightening there shall
be no rotation of the valve or flange.
Note 1
For bolt lengths not exceeding
8 diameters or 8 inches (203.2 mm) = 1/4 turn
For bolt lengths exceeding
8 diameters or 8 inches (203.2 mm) = 1/2 turn

Terms related to this page are below.

butterfly valves, butterfly valves, butterfly valves,butterfly valves, triple offset butterfly valves

triple offset butterfly valves, triple offset butterfly valves, concentric butterfly valves, ball valve

ball valves, pneumatic actuators, regulate flow, triple offset butterfly, flow control, flow control,

cast iron,  cast iron

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